JP2021070049A - Control method and control device of rolling machine - Google Patents

Abstract

To provide a control method and control device of a rolling machine which can prevent a linear wrinkle formed in a metal strip on a rolling machine inlet side from becoming drawing on a rolling machine outlet side at the time of rolling in the same rolling step.SOLUTION: A control method of a rolling machine 1 which includes a shape control actuator 15 and a flatness meter 16 installed on the outlet side of the rolling machine 1 comprises: a calculation step of calculating a control target value of the rolling machine 1 such that the flatness of a steel sheet W on the inlet side and outlet side of the rolling machine 1 satisfies the relation of the formula (1); and a control step of rolling the steel sheet W with the rolling machine 1 while controlling the shape control actuator 15 on the basis of the calculated control target value such that the steel sheet W on the outlet side of the rolling machine 1 becomes the target flatness.SELECTED DRAWING: Figure 1

Description

The present invention relates to a control method and a control device for a rolling mill.

Generally, steel sheets used for automobiles, beverage cans, etc. are continuously cast, hot-rolled, and cold-rolled, and after undergoing annealing and plating processes, they are processed according to their respective shapes. Further, after the hot rolling step and the cold rolling step, a temper rolling step is carried out in which the quality of the material is adjusted by applying a slight rolling reduction to the steel sheet according to the demand of the product.

Flatness is one of the qualities controlled in the rolling process. The flatness is evaluated by the elongation difference rate Δε [%] in the plate width direction of the plate. Further, the elongation difference rate Δε is indicated by “Δε = ΔL / L” based on the elongation difference ΔL in the plate width direction of the plate in a certain section (pitch) L, for example, as shown in FIG. ^The value multiplied by 5 is called in the unit of "I-unit".

Poor flatness of the steel sheet occurs because the elongation rates of the steel sheet in the plate width direction are not uniform during the rolling process, and when the flatness is large, the steel sheet wavy by the elongation difference in the plate width direction occurs. Such a steel sheet causes defects in a subsequent press or the like, and also causes uneven plating in the plating process. Further, if the flatness cannot be controlled well in the rolling process, a phenomenon called "narrowing down" occurs in which the steel plates are folded into the rolling stand.

Here, as a method of measuring the flatness during rolling, for example, the contact load between the steel plate and the roll is measured by using a flatness meter having a disk structure in which the roll is divided in the width direction and a load detection sensor is embedded in each roll. There is a method of calculating the shape. Further, as an actuator for controlling flatness (shape control actuator), a roll bender mechanism that applies bender force to both ends of the roll in order to control the shape by changing the axial deflection of the work roll, or a single taper There is an intermediate roll shift mechanism that shifts the intermediate roll in the width direction. There is also a VC roll mechanism that operates the roll crown by hydraulic pressure.

Further, as a general method of controlling the flatness of the steel sheet, for example, a device for measuring the flatness of the steel sheet after rolling is provided, and the flatness measured by the device is fed back to the rolling stand to control the shape control actuator (workpiece). Feedback control for operating the roll vendor) is performed (for example, Patent Document 1).

Especially in the case of low pressure lowering rate after hot rolling, the change in shape (flatness) in the hot rolling process, cooling process and winding process is predicted, and the shape after temper rolling is set to be optimal. A rolling control method for determining the value has also been proposed (for example, Patent Documents 2 and 3).

Japanese Patent No. 2964887 Japanese Patent No. 5971292 Japanese Patent No. 5971293

In a general rolling process, in order to prevent drawing, the flatness of the steel sheet during rolling is measured in real time, and the shape control actuator is operated so as to match the target value. However, when the flatness of the steel sheet before rolling is very poor, even if the plate shape after rolling is controlled to be flat, streak defects called drawing occur, resulting in a decrease in yield and a decrease in the operating rate of the rolling mill. Is a problem. For example, the method of Patent Document 1 performs rolling for the purpose of controlling the flatness after rolling, but does not assume the case where the flatness of the steel sheet before rolling is very poor (large). Further, although the methods of Patent Documents 2 and 3 assume the shape before temper rolling, the control is performed only from the viewpoint of shape control, and the control is not performed from the viewpoint of narrowing down suppression.

Therefore, when the steel sheet before rolling is deformed out of surface, the present inventors forcibly flatten the out-of-plane deformation directly under the roll of the rolling mill during rolling, so that shear stress is generated. However, it was found that the steel sheet buckled on the rolling mill entry side due to this shear stress to form linear wrinkles. Then, these linear wrinkles are crushed by a roll by rolling to form a drawing. As described above, when the flatness of the steel sheet before rolling is very poor, the present inventors do not control it from the viewpoint of suppressing narrowing down, otherwise linear wrinkles are formed on the steel sheet on the side entering the rolling mill during rolling. It was found that this linear wrinkle caused drawing on the exit side of the rolling mill.

The present invention has been made in view of the above, and in one and the same rolling process, it is possible to prevent linear wrinkles formed on the metal strip on the inlet side of the rolling mill during rolling from being drawn on the exit side of the rolling mill. It is an object of the present invention to provide a control method and a control device for a rolling mill that can be used.

ただし、式（１）において、Λ_２，ｉｎは圧延機入側での金属帯の平坦度、Λ_{２，ｏｕｔ}は圧延機出側での金属帯の平坦度、ａは形状制御の許容範囲を示すパラメータである。 The method for controlling a rolling mill according to the present invention is a method for controlling a rolling mill having a shape control actuator and a flatness meter installed on the exit side of the rolling mill, on the entry side and the exit side of the rolling mill. The calculation step of calculating the control target value of the rolling mill so that the flatness of the metal strip of the above satisfies the relationship of the following equation (1), and the metal strip on the exit side of the rolling mill is the target flatness. As such, it is characterized by including a control step of rolling a metal strip with the rolling mill while controlling the shape control actuator based on the calculated control target value.

However, in equation (1), Λ _{2, in} is the flatness of the metal strip on the rolling mill entry side, Λ _{2, out} is the flatness of the metal strip on the rolling mill exit side, and a is the allowable range of shape control. It is a parameter to show.

The method for controlling the rolling mill according to the present invention is that in the above invention, the calculation step is performed within a range in which the flatness of the metal strip on the entrance side and the exit side of the rolling mill satisfies the relationship of the above equation (1). The control step includes a step of setting a control target value so that the flatness of the metal strip on the outlet side of the rolling mill is as flat as possible, and the control step is based on the set control target value. It is characterized by including a step of rolling a metal strip with the rolling mill while controlling the above.

ただし、式（２）において、Λ_２，ｉｎは圧延機入側での金属帯の平坦度、Λ_{２，ｏｕｔ}は圧延機出側での金属帯の平坦度、ａは形状制御の許容範囲を示すパラメータである。 The rolling mill control device according to the present invention is a rolling mill control device having a shape control actuator and a flatness meter installed on the exit side of the rolling mill, and is on the entry side and the exit side of the rolling mill. The arithmetic processing unit that calculates the control target value of the rolling mill and the metal strip on the outlet side of the rolling mill are the target flatnesses so that the flatness of the metal strip of the above satisfies the relationship of the following equation (2). It is characterized by including a control unit for rolling a metal strip with the rolling mill while controlling the shape control actuator based on the calculated control target value.

However, in equation (2), Λ _{2, in} is the flatness of the metal strip on the rolling mill entry side, Λ _{2, out} is the flatness of the metal strip on the rolling mill exit side, and a is the allowable range of shape control. It is a parameter to show.

In the above invention, the control device for the rolling mill according to the present invention has the arithmetic processing unit within the range in which the flatness of the metal strip on the inlet side and the exit side of the rolling mill satisfies the relationship of the above equation (2). In, a control target value is set so that the flatness of the metal strip on the outlet side of the rolling mill is as flat as possible, and the control unit controls the shape control actuator based on the set control target value. The feature is that the metal strip is rolled by the rolling mill.

According to the present invention, when rolling a metal strip using a rolling mill having a shape control actuator, the shape control actuator is operated so that the flatness of the metal strip on the exit side of the rolling mill satisfies the above equation. As a result, the shape of the metal band can be made flat and the drawing can be prevented.

FIG. 1 is a schematic view showing a configuration of a rolling mill according to an embodiment. FIG. 2 is a diagram for explaining an allowable range of flatness of the steel sheet on the outlet side of the rolling mill. FIG. 3 is a diagram for explaining an approximate expression. FIG. 4 is a diagram showing the experimental results of Example 1. FIG. 5 is a schematic view for explaining the elongation of the plate.

Hereinafter, the control method and the control device of the rolling mill according to the embodiment of the present invention will be described with reference to the drawings.

[1. Rolling machine]
FIG. 1 is a schematic view showing a configuration of a rolling mill according to an embodiment. As shown in FIG. 1, the rolling mill 1 includes work rolls 11 and 12, backup rolls 13 and 14, shape control actuator 15, flatness meter 16, and flatness meter 17. The rolling mill 1 rolls a steel plate W, which is a metal strip, and is composed of a cold rolling mill. That is, in the embodiment, the case where the steel sheet W is rolled in the cold rolling step is targeted.

The work rolls 11 and 12 are arranged so as to face each other in the plate thickness direction of the steel plate W with a transport path for transporting the steel plate W in the rolling direction (longitudinal direction). The work rolls 11 and 12 continuously roll the steel plate W by rotating (rotating) while sandwiching the steel plate W sequentially transported along the transport path in the plate thickness direction.

The backup rolls 13 and 14 are arranged so as to face each other with the pair of work rolls 11 and 12 interposed therebetween. The upper backup roll 13 comes into contact with the outer peripheral surface of the upper intermediate roll from above, and presses the work roll 11 downward through the intermediate roll. As a result, the backup roll 13 applies the load required for rolling the steel plate W to the work roll 11. Further, the lower backup roll 14 comes into contact with the outer peripheral surface of the lower intermediate roll from below, and presses the work roll 12 upward via the intermediate roll. As a result, the backup roll 14 applies the load required for rolling the steel plate W to the work roll 12.

The shape control actuator 15 functions as a shape control unit that controls the shape of the steel sheet W after rolling by the rolling mill 1. The shape control actuator 15 shown in FIG. 1 imparts bending or inclination to the work roll 11 via the backup roll 13, thereby controlling the shape of the steel plate W after rolling by the rolling mill 1. Further, the shape control actuator 15 is controlled by a control device 2 described later.

The shape control actuator 15 is not particularly limited as long as it can change the ear elongation and the abdominal elongation of the steel plate W. For example, the shape control actuator 15 may be composed of a roll bender, an intermediate roll shift with a single taper, AS-U, a VC roll, and the like. For example, the work roll bender controls the plate crown of the steel plate W, and performs a roll bending operation of bending the work rolls 11 and 12 in the plate thickness direction of the steel plate W for the purpose of controlling the plate crown of the steel plate W. .. Work roll vendors are assigned to work rolls 11 and 12, respectively. For example, the upper work roll bender rotatably supports the roll shaft of the work roll 11 and applies a bending force of the steel plate W in the plate thickness direction to the work roll 11. At that time, the direction of the bending force applied from the steel plate W to the work roll 11 as the rolling reaction force (upward direction) is opposite to the direction of the load applied from the backup roll 13 to the work roll 11 (downward direction). Become. Further, the lower work roll bender rotatably supports the roll shaft of the work roll 12 and applies a bending force of the steel plate W in the plate thickness direction to the work roll 12. At that time, the direction of the bending force applied from the steel plate W to the work roll 12 as the rolling reaction force (downward direction) is opposite to the direction of the load applied from the backup roll 14 to the work roll 12 (upward direction). Become.

The flatness meter 16 is a first flatness meter installed on the entry side of the rolling mill 1 and measures the shape of the steel plate W on the entry side of the rolling mill 1 in real time. For example, the flatness meter 16 is composed of a roll type or a vibration type. The measurement result by the flatness meter 16 is input to the control device 2. Flatness is a shape parameter.

The flatness meter 17 is a second flatness meter installed on the outlet side of the rolling mill 1 and measures the shape of the steel plate W on the outlet side of the rolling mill 1 in real time. For example, the flatness meter 17 is composed of a roll type or a vibration type. The measurement result by the flatness meter 17 is input to the control device 2.

The flatness meters 16 and 17 are not particularly limited as long as they can measure the shape of the steel plate W on the entrance side and the exit side of the rolling mill in real time. Further, the flatness of the metal strip on the entry side of the rolling mill 1 may be measured by installing a flatness meter on the entry side of the rolling mill 1, but a flatness meter is used in the pre-process of the cold rolling process. If installed, the control device 2 may use the flatness measured in the previous step. In this case, the flatness meter 16 on the entry side of the rolling mill 1 is unnecessary.

The control device 2 is realized by a general-purpose information processing device such as a personal computer or a workstation, and has, for example, a CPU, a ROM, a RAM, or the like as main components. The control device 2 controls the rolling mill 1. Signals from the flatness meter 16 and the flatness meter 17 are input to the control device 2 during rolling. Then, the control device 2 executes various arithmetic processes based on the signals (measured values) input from the flatness meter 16 and the flatness meter 17, and controls the shape control actuator 15. A command signal is output from the control device 2 to the shape control actuator 15.

Further, the control device 2 has an arithmetic processing unit 21 and a control unit 22.

The arithmetic processing unit 21 has a measured value (inside flatness) input from the flatness meter 16 on the inlet side of the rolling mill during rolling, and a measured value (measured value (flatness on the entry side) input from the flatness meter 17 on the exit side of the rolling mill during rolling). The control target value for controlling the shape control actuator 15 is calculated by using the value determined according to the flatness on the protruding side) and the steel type of the steel plate W. For example, the arithmetic processing unit 21 calculates a control target value such that the steel plate W on the exit side of the rolling mill 1 has a target flatness according to the flatness of the steel plate W on the inlet side of the rolling mill.

The control unit 22 controls the shape control actuator 15 based on the control target value calculated by the arithmetic processing unit 21.

[2. Control method]
Here, the control method of the rolling mill 1 in the embodiment will be described.

First, in order to prevent the drawing of the steel plate W, it is important to measure the plate shape at the time of rolling in real time and control it to an appropriate shape. Therefore, in the control device 2, the shape control actuator 15 is operated so that the flatness of the metal strips on the entry side and the exit side of the rolling mill 1 satisfies the relationship of the equation (3).

In the formula (3), Λ _{2, in} is the flatness of the steel plate W on the inlet side of the rolling mill 1, Λ _{2, out} is the flatness of the steel plate W on the outlet side of the rolling mill 1, and a is the allowable shape control. It is a parameter indicating the range. The parameter a is a value determined by the steel type of the steel plate W, and is determined, for example, in a laboratory experiment or an actual machine experiment. The subscript in represents the entry side shape and out represents the exit side shape.

Further, the range satisfied by the equation (3) is illustrated in FIG. The range between the line C1 and the line C2 shown in FIG. 2 is a range that satisfies the equation (3). When flatness lambda _{2, in} which is the measurement value entry side is determined, depending on the entry side of the flatness lambda _{2, in,} flatness range at the outlet side of the between lines C1 and line C2 lambda _{2 ， Out} can be determined. That is, once the flatness Λ _{2, in on} the entry side is determined, the flatness Λ _{2, out} on the exit side can be set within a range in which the value on the line C1 is the upper limit value and the value on the line C2 is the lower limit value. Become.

Specifically, during rolling, the flatness meter 16 measures _{the flatness Λ 2, in on the entry side of the rolling mill 1. The measured flatness Λ 2, in} on the rolling mill entry side is input to the control device 2 in real time during rolling. The control device 2 _{substitutes the acquired flatness Λ 2, in} on the entry side into the above equation (3) to obtain the flatness Λ _{2, out} . The control device 2 controls the shape control actuator 15 so that _{the obtained flatness Λ 2, out is obtained. Then, the flatness meter 17 measures the flatness Λ 2, out} on the outlet side of the rolling mill 1, and inputs the measured value to the control device 2. As a result, the control device 2 compares the _{flatness Λ 2, out} , which is the control target value obtained by the above equation (3), with the flatness Λ _{2, out} , which is the measured value input from the flatness meter 17. Then, it can be determined whether the flatness of the steel plate W can be controlled within the target control range. In this way, the control device 2 controls the shape control actuator 15 so that _{the flatness Λ 2 and out} on the exit side fall within the control range determined by the above equation (3).

_{More preferably, by controlling the shape of the steel sheet W so as to be as flat as possible (Λ 2, out} = 0) within the range satisfying the above equation (3), the steel sheet W that is flat without drawing is formed. Can be manufactured. Here, when the flatness Λ ₂ is zero, it means that the steel plate W is flat. When the flatness Λ ₂ is a positive value, it means that the extension of the edge of the plate width is larger than that of the center of the plate width. When the flatness Λ ₂ is a negative value, it means that the elongation at the center of the plate width is larger than that at the end of the plate width. The control for making the shape of the steel plate W as flat as possible will be described with reference to FIG.

As shown in FIG. 2, when the flatness Λ _{2 and in} on the entry side are positive values, the steel plate W is as flat as possible within the range satisfying the equation (3) (between the line C1 and the line C2). A value closer to zero is set as a target value for _{the flatness Λ 2 and out} on the exit side in order to form such a shape. Then, a control target value for realizing the target value of the flatness Λ _{2 and out on} the output side is set, and the shape control actuator 15 is controlled based on the control target value.

_{Further, for the flatness Λ 2} on the entry side of the equation (3), the I-Unit distribution in the plate width direction is approximated by the quaternary equation of the equation (4), and the approximation coefficients λ ₂ and λ ₄ are obtained by the equation (5). It is a value obtained by linear conversion with, and represents the magnitude of extension of the plate width end portion with respect to the plate width center portion.

In equation (5), y ^* is the value shifted so that the I-Unit value at each point of the plate width becomes zero at the center of the plate width, and z is the relative plate width position so that both ends of the plate width are ± 1. It is a converted value. Further, FIG. 3 illustrates a diagram showing the relationship between ^{y * and z.}

For example, in the steel plate W having a large ear elongation, the elongation at the end of the plate width is larger than the elongation at the center of the plate width, and out-of-plane deformation occurs at the end of the plate width. If this ear-stretched steel plate W is rolled as before without applying the present invention, it occurs because the out-of-plane deformation on the plate width end side is forcibly flattened directly under the roll of the rolling mill 1. Due to the shear stress, the steel sheet W buckles on the rolling mill entry side, and linear wrinkles diagonal to the rolling direction are formed. The linear wrinkles are rolled by the rolling mill 1 to generate drawing.

Therefore, in the present embodiment, when the ear-stretched steel plate W is rolled by the rolling mill 1, the control device 2 makes the plate shape on the outlet side of the rolling mill 1 abdominal stretch according to the above equation (3). , Controls the shape control actuator 15. As a result, the elongation of the plate width end of the steel plate W on the exit side of the rolling mill 1 is reduced, and the state in which the elongation of the plate width end of the steel plate W on the inlet side of the rolling mill 1 is relatively large is alleviated. It can be done and the aperture can be prevented.

Similarly, when the belly-stretched steel plate W is rolled by the rolling mill 1, the control device 2 sets the shape control actuator 15 so as to reduce the plate width end portion more than the plate width center portion according to the above equation (3). Control. As a result, the elongation of the central portion of the plate width on the exit side of the rolling mill 1 is reduced, and the state in which the elongation of the central portion of the plate width on the inlet side of the rolling mill 1 is relatively large is alleviated. Occurrence can be prevented.

(Example 1)
In Example 1, a mild steel plate having an inlet side plate thickness of 0.55 mm, an outlet side plate thickness of 0.40 mm, and a plate width of 1100 mm was rolled. The set values of the unit tension were set to 100 MPa on the inlet side and 80 MPa on the outlet side. As the rolling mill 1, a 6Hi rolling mill was used. The rolling mill 1 is provided with a work roll bender as a shape control actuator 15. A roll-type flatness meter is installed on the entrance side and the exit side of the rolling mill 1. Further, the parameter a of the above equation (3) was set to a = 50I-Unit by investigating the conditions under which rolling could be performed without drawing in the past operation results. Then, the control device 2 operates the work roll bender so that the shape of the steel plate W on the outlet side of the rolling mill 1 is as flat as possible within the range in which the measured value of flatness satisfies the relationship of the above equation (3). did. The results of this experiment are shown in FIG.

As shown in FIG. 4, in the conventional operation, the throttle is generated at a ratio of 2 coils out of 4300 coils. On the other hand, in the first embodiment to which the above-described embodiment is applied, the number of times the throttle is generated is 0 out of 4300 coils. As described above, according to the first embodiment, by applying the present invention, it is possible to roll without causing drawing.

In the above-described embodiment and the first embodiment, the case where the steel sheet W is rolled in the cold rolling step has been described, but the present invention is not limited to this. For example, the present invention is also applicable to the case of rolling a thin hot-rolled material with a single-machine mill (including temper rolling with a hot-rolled skin pass facility). That is, the present invention can also be applied to a metal strip rolled in a temper rolling step.

1 Roller 2 Control device 11, 12 Work roll 13, 14 Backup roll 15 Shape control actuator 16, 17 Flatness meter 21 Arithmetic processing unit 22 Control unit

Claims (4)

A method for controlling a rolling mill having a shape control actuator and a flatness meter installed on the outlet side of the rolling mill.
A calculation step of calculating a control target value of the rolling mill so that the flatness of the metal strip on the entrance side and the exit side of the rolling mill satisfies the relationship of the following equation (1).
A control step of rolling the metal strip with the rolling mill while controlling the shape control actuator based on the calculated control target value so that the metal strip on the exit side of the rolling mill has the target flatness. A method for controlling a rolling mill, which comprises.

However, in equation (1), Λ _{2, in} is the flatness of the metal strip on the rolling mill entry side, Λ _{2, out} is the flatness of the metal strip on the rolling mill exit side, and a is the allowable range of shape control. It is a parameter to show. In the calculation step, the flatness of the metal strip on the exit side of the rolling mill is within a range in which the flatness of the metal strip on the inlet side and the exit side of the rolling mill satisfies the relationship of the above equation (1). Includes steps to set control target values that are as flat as possible
The control of the rolling mill according to claim 1, wherein the control step includes a step of rolling a metal strip with the rolling mill while controlling the shape control actuator based on the set control target value. Method. A control device for a rolling mill having a shape control actuator and a flatness meter installed on the outlet side of the rolling mill.
An arithmetic processing unit that calculates a control target value of the rolling mill so that the flatness of the metal strip on the entrance side and the exit side of the rolling mill satisfies the relationship of the following equation (2).
With a control unit that rolls the metal strip with the rolling mill while controlling the shape control actuator based on the calculated control target value so that the metal strip on the exit side of the rolling mill has the target flatness. A rolling mill control device comprising.

However, in equation (2), Λ _{2, in} is the flatness of the metal strip on the rolling mill entry side, Λ _{2, out} is the flatness of the metal strip on the rolling mill exit side, and a is the allowable range of shape control. It is a parameter to show. In the arithmetic processing unit, the flatness of the metal strip on the exit side of the rolling mill is within a range in which the flatness of the metal strip on the inlet side and the exit side of the rolling mill satisfies the relationship of the above equation (2). Set the control target value so that
The control device for a rolling mill according to claim 3, wherein the control unit rolls a metal strip with the rolling mill while controlling the shape control actuator based on the set control target value.

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